#include<reg52.h>
sbit BEEF = P2^ 5; 

void delay_tenus(int time)
{
	while(time--);
}
void main()
{
	int i = 3000;
	while(1)
	{
		while(i--)
		{
		BEEF = 0;
		delay_tenus(100);
		BEEF = 1;
		delay_tenus(100);
		}
		BEEF = 0;
	}
}